The primary goal of this research is to develop a high resolution, rapid scanning Fourier Transform mass spectrometer which can be used in direct analysis of mixtures. The proposed spectrometer is based on the principles of ion cyclotron resonance which allow gaseous reagent ions to be stored for as long as 20 seconds in a static ion trap and mass analyzed by exciting and detecting the cyclotron motion of the ions. Attention will be focused on direct analysis for low volatility compounds which cannot be separated by gas chromatography. To achieve selectivity, the instrument will rely upon computer-controlled temperature programming of the direct insertion probe, specific reagent gases to ionize only certain components of the mixture, high mass resolution, and multiple ion monitoring. The technique will be applied to analysis for hypermodified nucleotides implicated in chemical carcinogenesis.